The present invention generally relates to capsules for containing beverage-forming ingredients, a beverage producing system for use in connection with such capsules as well as to methods for producing beverages using such capsules.
The background of the present invention is the field of capsules which are adapted to contain beverage or other comestible (e.g., soup) ingredients. By means of an interaction of these ingredients with a liquid, a beverage or other comestibles, such as for example soups, can be produced. The interaction can be for example an extraction, brewing, dissolution, etc. process. Such a capsule is particularly suited to contain ground coffee in order to produce a coffee beverage by having hot water under pressure enter the capsule and draining a coffee beverage from the capsule.
The systems and methods for obtaining fluid comestibles from substances containing capsules are for example known from U.S. Pat. No. 5,402,707. The capsule 101 as shown therein in FIG. 1 has a frustoconically-shaped cup 102 which may be filled e.g. with roasted and ground coffee 103 and which is closed by a foil-like tear face cover 104 welded and/or crimped to a flange-like rim which extends laterally from the side-wall of cup 102. A capsule holder 111 comprises a flow grill 112 with relief surface element members 113 and an annular chamfered rim 114. The capsule holder 111 is accommodated in its support 115 which has a lateral wall 124, and a bore 127 for the passage of extracted coffee beverage.
As can be seen from FIG. 1, the extraction system further comprises a water injector 107 having a water inlet channel 120 and an annular element 108 with an internal recess of which the shape substantially corresponds to the outer shape of the capsule. On its outer part, the bell member 108 comprises a spring 122 holding a ring 123 for releasing the capsule on completion of extraction.
In operation, a capsule 101 is placed in the capsule holder 111. The water injector 107 perforates the upper face of the cup 102. The lower tear face 104 of the capsule rests on the radially arranged members 113 of the capsule holder 111. The water is injected through the channel 120 of the water injector 107 and impinges on the bed 103 of coffee. The pressure in the capsule 101 increases and the tear face 104 increasingly follows the shape of the radial opening relief members 113. When the constituent material of the tear face reaches its breaking stress, the tear face tears along the relief members. The extracted coffee flows through the orifices of the flow grill 112 and is recovered in a container (not shown) beneath the bore 127.
The principles of this extraction process as far as it can be maintained in connection with the present invention can be summarized as follows:
a sealed capsule is inserted in capsule holder means;
the capsule holder means is then associated with water injection means of the machine such that an annular element (108 in FIG. 4) surrounds the capsule;
in a first wall of the capsule at least one opening is generated, and
water entering the capsule through the opening in the first wall is interacting with the ingredients in the interior of the capsule and the thus produced beverage is then drained from at least a second opening is created in the second wall.
The ingredients in the capsule constitute the “bottleneck” of the flow path of the water and will therefore cause a pressure drop between the upstream and the downstream side of the liquid flow through the capsule, which pressure drop will even increase during the interaction between the liquid and the ingredients for example due to a swelling of the ingredients. Correspondingly it has to be assured that the only water flow is actually taking place through the interior of the capsule (arrow A1) and that no water can flow from the water injector into the interstice between the annular enclosing member 108 and the exterior of the capsule 101 and then to the draining bore 127 of the device. The arrow A2 illustrates this undesired external water flow path. With other words, any water flow exterior to the capsule 101 has to be stopped (or at least hindered to a substantial degree) by a sealing engagement being positioned in the interstice between the annular member 108 and the capsule 101 and in the flow path between the water injector and the beverage-draining bore. In the prior art embodiment shown in FIG. 1 such sealing engagement can be achieved by the pinching engagement between the annular member 108, the flange-like rim of the side wall of the capsule 101 and the capsule holder.
In case the sealing engagement is not working properly and water is flowing outside the capsule, no pressure sufficient to cause the tearing of the tear face will be built up inside the capsule, or alternatively, a too low pressure will be causing partial tearing of the tear face and therefore only a poor extraction of the substance, consequently, leading to the delivery of a low quality beverage. In such a scenario water will be drained from the beverage production device without having interacted or fully interacted under sufficient pressure conditions with the ingredients contained in the capsule.
In the prior art improvements are known in which this sealing engagement is further improved by lining the inner wall of the annular member with a rubber-elastic material. With other words, according to said prior art the sealing engagement is assured by structures fixed to or attached with the beverage-producing device. This has disadvantages in that after the use of a substantial number of capsules a wearing off of the fixed sealing means can take place such that the quality of the produced beverage is increasingly deteriorated by water passing the no longer properly efficient sealing.
Any “leak” at the exterior of the capsule reduces the pressure build-up inside the capsule. On the other hand, it is well known that a sufficient extraction pressure is a key factor for the quality of espresso-style coffee.
Accordingly, there is a need for improvements in the sealing means of such capsules, and these are now provided by the present invention.